


9/3

by ChineseCabbage



Series: Begin Again [3]
Category: Kamen Rider Build
Genre: Birthday, Birthday Cake, M/M, Marriage Proposal
Language: English
Status: Completed
Published: 2019-05-25
Updated: 2019-05-25
Packaged: 2020-03-17 04:14:41
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,511
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18957661
Author URL: https://archiveofourown.org/users/ChineseCabbage/pseuds/ChineseCabbage
Summary: Kiryuu Sento was never exist to begin with.Well, Ryuuga wants to proof him that he's wrong. Kiryuu Sento is exist. He exists since the day he found Ryuuga on September 3rd.





	9/3

**Author's Note:**

> This is set after KR Cross Z and Grease movie so it might contain huge spoiler.
> 
> I didn't watch the movie yet but read spoilers, so I kinda understand the gist of SenBan situation in the new alternative-universe they created. So please spare every mistakes that is not canon-compliant //bows//

If someone told him in the past that there will be a day when, he, Banjou Ryuuga, a professional boxer, will do something as domestic as baking in the future, he would punch that person to another dimension.

But here he is, anyway; baking.

Ryuuga learns this skill from his new part-time job in a bakery. He's proud of himself somehow. One year into living a new life in a new world, Ryuuga's domestic skill expands widely. Say goodbye to the cup-ramen Ryuuga in the past; now he can cook (simple dishes). He can do laundry. He can do house-cleaning. Recently he can bake. All thanks to Sento who turns out to be such a good for nothing aside from tinkering new inventions in his workshop.

Ryuuga smirks smugly. That genius physicist Kiryuu Sento, surely will die in 7 days if Ryuuga is not around to save their ass with survival living skill.

The oven beeps, and Ryuuga hums his way toward it. He accidentally burns his finger as he forgot to cover his hand before touching the smoldering hot handle. _Beginner's mistake._

But what he takes out from the oven, can't even be classified as a mistake anymore.

The cake was supposed to be a simple sponge cake in a shape of a rabbit's head. But what's coming from the oven looks more like a _hannya_ mask.

"Huh, did I do something wrong?"

Well, Ryuuga never do any baking in his bakery part-time in the first place, to be honest. He's in charge for the cash register, and sometimes sneaking a glance to the baking station in his spare time. Baking looks easy. There's a recipe and instructions he only needs to follow. Okay, he did few mistakes along the way but ....

Ryuuga sighes. He reaches his phone and calls Misora.

 

*

 

"You should have called me since the very start! I knew it will end up like this!" Misora cries at the sight of a _Hannya_ cake on the kitchen table, "what a way to waste ingredients!"

"Okay, I'm sorry," Banjou apologizes, "can you fix it?"

"What to fix? I told you to put the icing after the baking is done! I told you to wait for me before doing anything!"

"There's a recipe. There are instructions. And I see a few baking progress in-- okay, okay, I'm sorry. I'll shut up."

"And buy a new set of the ingredients!"

"Yes, yes."

Banjou leaves the kitchen. Misora takes another look to the Hannya cake before let out a frustated groan. Thank goodness they still have another 5 hours before the usual time Sento arrives at home.

 

*

 

With a new set of ingredients and a guide who bakes more often than him, Ryuuga throws the _Hannya_ cake to a trash bin 500 meters away from the house; no way in hell he will let Sento sees any tiny trace of that abomination of a cake.

"So, you separate the yolk from the whites like this ...."

Ryuuga blinks, "err, I need to do that?!"

"The recipe said you need 4 pieces of egg yolk."

"Egg yolk is different from an egg?" Ryuuga dumbfoundedly asks.

Misora sighes.

"Honestly," she says, "you can asks me or Sawa-san to bake it for you ... or asks Himuro-san, he probably can get the best baker in the country to do it," she adds fast in murmurs. Having a big shot in their circle of friends has its own perks. Misora and Sawa always enjoy the gifts Gentoku brings whenever he comes back from accompanying his father, the Minister of Japan, to visit various prefectures.

Ryuuga stares at Misora judgingly.

Misora avoids his eyes and continue separating egg yolks for Ryuuga.

Ryuuga clears his throat; a habit Misora learns Ryuuga will do when he feels awkward or bashful, "that won't do. It won't feel like I'm thanking him enough."

"So this is for the sake of your gratitude?"

Ryuuga shows a vague nod.

"Why it has to be today? You can give your gratitude when you're finally get some gist of baking."

"Because today, two years ago, Sento found me."

Misora hands stop moving.

Ryuuga snorts, "imagine what will happen to me if he didn't find me that day."

Seems like Misora absorbing this story for a moment, before she send another question, "then why did you want to write 'happy birthday' instead on the icing?"

"It's ... well, like hell I'll write _thank you_ on the cake right?! Take the birthday as a camouflage. Come on, what should I do next after getting the egg yolk?"

Misora rolls her eyes at Ryuuga's horrible wat to change their subject, and sends him _that_ look. That certain look that makes Banjou feels bad from hiding something from her.

Banjou sighs again. After opening and closing his mouth for a while, he finally finds the word to start, "Sento ... he's not showing it, but I know what he's been thinking."

"Huh?" Misora blinks.

"Locking himself up in his workshop all day, that idiot still thinks he doesn't belong here. Because a person named Kiryuu Sento was never exist in the first place. Because he was made from Katsuragi Takumi and Satou Tarou, yet he's neither of them.

_And I want to proof that you're wrong, Sento._

"That's why, I arranged something with Gentoku."

Misora tilts his head to the suddenly smiling Ryuuga.

"What is it?"

"I asked Gentoku to give him registry documents for citizenship. Sento's ID card should be finished by today," Accompanying his answer, Ryuuga shows a V sign with his fingers. His smile is too bright, Misora feels lightheaded.

She raises her voice in a whisper "you ask government officer to forge a registry document?!"

"Well, Gentoku agreed anyway. It's for the best."

"How about your documents?"

Ryuuga shakes his head, "I can't, and I don't need one. There's another Banjou Ryuuga exists here in this world and I share the same identity with him. But there's only one Kiryuu Sento, and the purpose of this whole thing is because I want to slap that fact to that idiot's face. He's exists. His citizenship will be the proof of his existence."

"So ... I guess you made the date when you meet Sento as his birthday in the registry?"

"Well, I need a birthday date that only owned by Sento," Ryuuga shrughs and explains, "Not Katsuragi Takumi or Satou Tarou's birthday date."

"There's also another date available, though; the date when Evolto finds him."

"That date," Ryuuga interrupts loudly, "is an unlucky day. Full of bad energy. We should throw away soybeans at our front door."

"You treat it like _setsubun_."

"Yeah. It's mine and Sento's _setsubun_ ," Ryuuga nods to Misora.

He interprets the look on Misora's face as admiration for this genius idea. Misora, on the other hand, is actually feels totally helpless.

_Did Banjou doesn't realize he's just being very possesive to Sento by using their meeting date as his birthday? Didn't he just show his jealousy toward Evolto and refuse to use the date Evolto found Sento despite that date is actually and technically more correct?_

"Man, am I genius or what?" Ryuuga snorts at his own problem-solving skill.

"Banjou, you're such an idiot."

"Eh?!"

Sawa needs to hear this, decides Misora. Misora needs to vent this to Sawa, or else she wants to crush her own head from frustation because Ryuuga is such a hopeless, slow, idiot!

 

*

 

"Happy Birthday, Sento!!!"

"Yeaaaaay!!!"

Sento is dumbfounded. He blinks a few time to make sure the whole Nascita gang sitting on the dining table in front of him really makes that funny smug expression on their face.

"What?"

"Dude, what a dry reaction," comments Kazumin.

"It's not 'what', idiot. Just blow the candle already!" Says Ryuuga, sitting right across him, just behind a cute rabbit cake with 8 cupcakes forming the words ' _tanjoubi omedetou_ \--happy birthday' surrounding it.

"But today is not my birthday ...?" is Sento's response in confusion.

"From today, it is. Just accept it," says Sawa with a smile.

Beside him, Gentoku put an ID card on the table, "it's official in the registry; Kiryuu Sento. Born September 3rd."

"Come on, just blow the candle first before it ruined the cupcakes," Misora urges him.

"There's a rabbit cake anyway? It's still enough for everybody," Sento points out. Why is the ID card? Why is the birhday date? Why are there two different birthday cakes? Can they just bake a square cake and draw rabbit and write happy birthday on top of it? He still looks very confused but at least, he walks across the room and sit down on the only available space. 

"Oh, that cake is not edible. Banjou fails to bake it for the nth time and I decide to just decorate the last one anyway," explains Misora, "and then we bought the cupcakes last minute."

"I see, I don't expect much from Banjou. It's okay, I don't like sweets anyway."

"Oi, is that your way to say thanks?!

"--And dad says hi, he can't leave Nascita at this hour so he couldn't come."

"Okay,"

"Just blow the candle."

Sento chuckles and blows the candle, "thanks, everyone."

"What a way to say thanks," grunted Ryuuga.

Sento smiles, "no, I don't understand why you prepare this to such an extend. But I really feel thankful, Banjou."

Ryuuga refuse to look at Sento as he murmurs, "who said I do any--ouch!!"

Misora kicks his shin under the table.

"So," Sento takes a cupcake and examine it in interest, "why did you choose September 3rd as my birthday?"

"For no reas--ouch!!"

Misora kicks Ryuuga again for his indifference answer. She clicks her tongue, "it's the day you guys first met."

Everyone gets their own cupcake and takes a bite as Sento muses, "ah, the day when the zipper on your pants was open for the whole day."

Loud choked noise can be heard from every corner.

"W-what?!"

"What's that supposed to be mean?!"

"Sento you bastard, is that the only thing you remembered?!"

Looking at the flabbergasted face around him, and especially the flabbergasted _and_ bashful face of Ryuuga, Sento laughs heartily.

"Thanks, now I won't forget it for the rest of my life!"

"Forget it already!!"

Sento laughs again. Ignoring Ryuuga's protests accross the table, he finally takes a look at his own ID card.

It's not Kisaragi Takumi or Satou Tarou's name, but his own.

It's not Kisaragi Takumi or Satou Tarou's birthday, but his own.

Such a quick, simple fix, very much what that muscle-brained simpleton will do.

Kiryuu Sento was never existed. So is this how Ryuuga telling him that the Sento he knows exists since the day when they first met?

"By the way," Gentoku interrupts, and he takes another card out of his pocket, asking Ryuuga while doing so, "why did you only ask for Sento's ID card? It will be troublesome if officers find you without any identity documents."

He puts another ID card right besides Sento's.

Ryuuga frowns, "I told you I can't and don't need one. What about the other Banjou Ryuu--HUH?!"

"Only need a quick fix on your name and some stuff and it's done. You're no longer was born in obgyn at Yokohama--"

"THIS IS A VERY LAZY FIX! WHAT HAVE YOU DONE?!"

"Come on, don't petty small details. I don't have all day forging your registry, you know."

"If you gotta change my name, than change every single character! Fixing my last name from Banjou to Kiryuu is a fucking lazy move!!"

Misora drops his cupcake. Now everybody observes Ryuuga's new ID card. The name is indeed written as Kiryuu Ryuuga, also born on September 3rd.

" _Hige_ , this is genius!" Misora and Sawa squeals.

" _Hige_ , you're fucking asshole!" Ryuuga doesn't share the same opinion.

Kazumin nods, "well, it makes sense and easy in bureaucracy level. Congratulations, Banjou."

"Why did you congratulate me for?!"

And as if he's deaf of Ryuuga's protest for this whole setting, Sento smirks playfully, "welcome to my family, Banjou. Oh wait, you're also a Kiryuu now."

"No way! Give me back my last name!"

 

*

 

Staring at the cute rabbit cake which was said is hiding a hideous look under it's perfect icing, Sento wonders.

"Why are you staring at my cake like that?" Banjou asks in a warning tone.

"I just wonder how much a failure this cake turns out under your hands. So, in the name of science ...."

Sento takes a knife, ready to slice the the cake.

"Hey, stop!"

But nobody stops Sento. All of Ryuuga's so-called friends is turning their back against him and now watching Sento create a new dramatic discovery.

The knife smoothly cut the icing for a mere one second before stopped. It won't budge anymore no matter how much strength Sento put to slice it down.

Banjou backs off from the crowd in the dining table slowly, trying to find a shadow to hide there forever.

Sento, curiously, use the knife to knock the cake, which somehow produce a loud thump like a brick.

"It's a big failure," admits Misora, "I try my best to guide him. But at least this one doesn't look as poisonous as his first try, or moaning and wiggling miserably like the second one."

"Wait, what?" Kazumin, Sawa and Gentoku can't follow. Is she still talking about pastry?

"Unbelievable," exclaims Sento, nodding like he's just discovering a new kind of mineral or something, "this cake might be as tough as a metal. It's unbelievable how it's all started with flour and eggs."

"I welcome all of you to shut the fuck up," murmurs Ryuuga.

Sento chuckles, suddenly sounds very kind somehow and Ryuuga doesn't know how to proceed this kind-looking mad scientist as he says, "well, there's a start for everything. I'm looking forward for your creation next year. It has become your birthday too, anyway. Let's celebrate."

Ryuuga's face looks like as if Sento was just insulting him and his whole family, "seriously, you only need to say a fake thank you and I'll be fine."

"I'm serious, Banjou," coax Sento, as he smiles brightly, "bake me a birthday cake every year from now on, okay?"

Proportionally inverse with Kazumin and Gentoku's horror face, Sawa gasps and Misora covers his gaping mouth with his palms.

Ryuuga, meanwhile, choose to become the usual musclehead he is and retorts offhandedly, "am I your personal baker or something."

"That will do too," muses Sento lightly.

The musclehead still foolishly takes it as a challenge, "someday I'll bake a cake that's so delicious it will make you cry. Just wait and see, Kiryuu Sento."

"Yep. Take your time. I'm ready to wait for the rest of my life, Kiryuu Ryuuga."

"Oi, are you mocking me?! You wanna fight?!"

But the rest of their gang is seeing something more than just a challenge. And looking at that playful glimpse shining on Sento's intelligent eyes, they suddenly pity Ryuuga. There's no way Ryuuga can escape this man in this lifetime.

That muscle-brain of his is clearly wrapped under Sento's calculating fingers.

**Author's Note:**

> @Machbanana give me this prompt and I'm pretty much just write everything she wants to happen between SenBan in their new world. So, please don't forget thank her for this wonderful idea!
> 
> Some points for this story:
> 
> 1\. Yeah. Gentoku somehow accidentally marrying Sento and Banjo under Japan's citizenship registry (well, they might be written as brothers but still: BANJOU IS REGISTERED UNDER KIRYUU'S FAMILY NAME XD).
> 
> 2\. Setsubun: on this day in Japan, family will throw soybeans on their front door or to a family member who dressed like oni/demon to avoid bad luck (better explanation please check Google!). Banjou treats Evolto like an evil being need to get ridded off every year LOL.
> 
> 3\. In Japan, there are so many ways to say that you love or want to live the rest of your life with someone. Some might say 'will you marry me' straightforwardly but there are subtle way to say that too. Saying something like "I want to eat your cooking everyday" or probably "Yea I can stand for your shit forever" has the same gist (cmiiw). For me personally, the second way sounds romantic on its own way. So yeah, Sento proposed to Banjou in front of the whole gang but too bad Banjou is too slow to catch it (thou Sento kinda expects that. He can be cunning like that).
> 
> I like to think that their relationship might not defined by real status since both of them are huge idiots who never honest with their own thought and feeling. But they can't leave each other still.
> 
> Last, I'm sorry if this one is badly written with messy grammar. I'll try to fix it once I logged in with my PC (writed this one on my phone). I wish you guys enjoy the story as much as I enjoy writing it.


End file.
